Dna and Fingerprints
Research papers on DNA fingerprint evidence explicate the difference between regular fingerprint evidence and DNA fingerprint evidence and focus on what criminal justice experts call the "DNA fingerprint".
Traditionally, research papers on the term "fingerprint" refer to patterns that are highly characteristic to an individual's ridged skin of the distal finger phalanges. With regard to individual specificity, research papers on DNA fingerprinting point out that the practice is comparable to its namesake. However, for the layman, this is where the similarities stop. Although classical fingerprints can tell us whether a suspect has been at a crime scene or not, there are currently no means to correlate fingerprints to personal characteristics, such as race, gender, or population background. Despite this reasoning, most people are familiar with the concept of traditional fingerprints and therefore the analogy between DNA fingerprinting and traditional fingerprinting is quite useful and commonly made.
Fingerprints and DNA Profiling
In comparing and contrasting traditional fingerprints to their DNA profiling counterparts, it seems that the two techniques are related on a fundamental genetic level. Researchers and scientists believe that characteristics of the traditional, or dermatoglyphic fingerprint, such as the ridge count, are determined by several genes. In forensic DNA evidence, minutiae in the dermatoglyphic fingerprint patterns are analyzed. The minutiae result from a combination of genetic and non-genetic events during pregnancy.
DNA fingerprints are similar, in that they too arise form genetic information. Although various types of DNA fingerprinting have been developed since the mid-1980's, state-of-the-art DNA profiling depends on what are called "short tandem repeat" polymorphisms (STRs). STRs are segments of DNA that show considerable variation between individuals and can be explained in the following way:
- Criminal investigators have adopted a standard using 13 STR core loci for identifying genetic differences between people.
- These loci are not genes but areas of "junk" DNA found in all human beings.
- Testing one locus gives a 1-in-500 chance that a particular sample of DNA came from a particular individual.
- Testing all 13 loci changes the odds 1 in 82 billion.
In short, with DNA testing, it is not possible to obtain all necessary information to definitively establish an individual's identity.
This is not the case, however, with dermatoglyphic fingerprints. It seems that with dermatoglyphic fingerprints it is possible to obtain all of the information from all 10 finger pads, with no discrepancies. In essence, fingerprints provide a more comprehensive picture.Putting this in perspective it can be asserted that since only a small portion of human DNA units are available for analysis, the DNA fingerprint is more analogous to a partial fingerprint than a traditional fingerprint. Just as a certain number of points of comparison are necessary to determine two fingerprints are from the same individual, so too is it necessary to compare a certain number of points in the DNA fingerprint to establish identity.